Transcriptome Analysis of the Triatoma infestans (Hemiptera: Reduviidae) Integument

Abstract

The insect integument, formed by the cuticle and the underlying epidermis, is essential for insect fitness, regulation of lipid biosynthesis and storage, insect growth and feeding, together with development progress. Its participation in insecticide resistance has also been outlined. Triatoma infestans Klug (Hemiptera: Reduviidae) is one of the major vectors of Chagas disease in South America; however, genomic data are scarce. In this study, we performed a transcriptome analysis of the nymph integument in order to identify which genes are expressed and their putative role. Using the 454 GS-FLX sequencing platform, we obtained approximately 144,620 reads from the integument tissue. These reads were assembled into 6,495 isotigs and 8,504 singletons. Based on BLAST similarity searches, about 8,000 transcripts were annotated with known genes, conserved domains, and/or Gene Ontology terms.The most abundant transcripts corresponded to transcription factors and nucleic acid metabolism, membrane receptors, cell signaling, and proteins related to cytoskeleton, transport, and cell energy processes, among others. More than 10% of the transcripts-encoded proteins putatively involved in the metabolism of fatty acids and related components (fatty acid synthases, elongases, desaturases, fatty alcohol reductases), structural integument proteins, and the insecticide detoxification system (among them, cytochrome P450s, esterases, and glutathione transferases). Real-time qPCR assays were used to investigate their putative participation in the resistance mechanism. This preliminary study is the first transcriptome analysis of a triatomine integument, and together with prior biochemical information, will help further understandthe role of the integument in a wide array of mechanisms.

A fatty acid synthase gene (FASN3) from the integument tissue of Rhodnius prolixus contributes to cuticle water loss regulation

“…Three FASN genes ( fatty acid synthase RPRC000123, RPRC000269 and RPRC002909 ) were recently reported in the R. prolixus genome (Majerowicz et al ., ) and additionally, two FASN gene fragments are present ( RPRC000168 and RPRC000923 ) with most of the enzymes’ known domains missing (https://www.vectorbase.org/organisms/rhodnius-prolixus; Mesquita et al ., ). In T. infestans , a search of an integument transcriptome showed the presence of two integument FASN genes orthologous to RPRC002909 and RPRC000123 (Calderón‐Fernández et al ., ). Evidence that the corresponding FASN activities are differentially affected by chemical insecticides has previously been recorded in T. infestans (Juárez, ).…”

Synthesis and secretion of volatile short‐chain fatty acids in Triatoma infestans infected with Beauveria bassiana

“…There is no information to date about the genes involved in the synthesis of straight and branched short-chain fatty acids in insects. Using parallel information available from plants and mammals (Van der Hoeven & Steffens, 2000), two sequences with high identity to branched-chain amino acid transport system (brnq) and branched-chain alpha-keto acid dehydrogenase (bckdc) genes were detected in an EST library from T. infestans cuticle (Calderón-Fernández et al, 2017). In an attempt to begin to understand their roles in the synthesis of volatile compounds, their expression levels were evaluated in infected individuals.…”

“…Reactions containing primer pairs without template were also included as blank controls. The sequences corresponding to the putative branched-chain amino acid transport system (Ti-brnq gene) and the putative mitochondrial branched-chain alpha-keto acid dehydrogenase (Ti-bckdc gene) were obtained from an expression sequences tagged (EST) library synthesized from the cuticle of T. infestans nymphs (GenBank, BioProject PRJNA314811) (Calderón-Fernández et al, 2017). The sequences IDs are JAR98428 for Ti-brnq and JAR97322 for Ti-bckdc.…”

Tracing the coevolution between Triatoma infestans and its fungal pathogen Beauveria bassiana

“…Pyrethroid-resistant insects have a thicker cuticle, together with a higher content of epicuticular hydrocarbons compared to susceptible insects; these biochemical data correlated well with reduced penetration of the insecticide and thus a decrease in the effective dose Pedrini et al, 2009). Cuticle thickness is most likely related with the overexpression of selected cuticle protein genes from the integument of pyrethroid-resistant insects (Calderón-Fernández et al, 2017).…”